The major objectives of the proposed research are to determine: a. whether specific genetic markers exist in the maturity-onset diabetic or in individuals who have predisposing genes for diabetes. b. whether the differing susceptibility of various ethnic groups to maturity-onset diabetes is related to the pesence or absence of these genetic markers. c. to establish the relative role of other factors such as age, nutrient intake, physical activity, obesity, stress, etc. in the causation of diabetes in genetically susceptible individuals. d. the definition of possible preventative factors relating to diabetes in high prevalence populations. On the basis of these findings it is hoped that intervention programmes might be undertaken. It is hoped to achieve these objectives by measurement of genetic markers (e.g., tissue typing, red blood cell enzymes and serum proteins with known gene loci). The studies will be carrid out on Caucasian, Melanesian, Polynesian, Micronesian, and American Indian populations. Such a study provides a broad spectrum of ethnic groups with varying susceptibility to diabetes. It will allow the comparison of genetic and various environmental factors which may influence the development of diabetes in these populations.